# Softness suppresses fivefold symmetry and enhances crystallization of binary Laves phases in nearly hard spheres

## TL;DR

This study shows that introducing softness in the interparticle potential of nearly hard spheres promotes the spontaneous crystallization of binary Laves phases by suppressing fivefold symmetry, which is typically a barrier to crystallization.

## Contribution

It demonstrates through simulations that softness in interparticle interactions facilitates the formation of binary Laves phases in nearly hard spheres, a phenomenon not observed in purely hard-sphere systems.

## Key findings

- Softness suppresses fivefold symmetry in the binary fluid phase.
- Softness enhances the crystallization of Laves phases.
- Binary Laves phases can form spontaneously in nearly hard spheres with soft interactions.

## Abstract

Colloidal crystals with a diamond and pyrochlore structure display wide photonic band gaps at low refractive index contrasts. However, these low-coordinated and open structures are notoriously difficult to self-assemble from colloids interacting with simple pair interactions. To circumvent these problems, one can self-assemble both structures in a closely packed MgCu2 Laves phase from a binary mixture of colloidal spheres and then selectively remove one of the sublattices. Although Laves phases have been proven to be stable in a binary hard-sphere system, they have never been observed to spontaneously crystallize in such a fluid mixture in simulations nor in experiments of micron-sized hard spheres due to slow dynamics. Here we demonstrate, using computer simulations, that softness in the interparticle potential suppresses the degree of fivefold symmetry in the binary fluid phase and enhances crystallization of Laves phases in nearly hard spheres.